Eraser support for mechanical pencils



Nov. 12, 1957 J. MASTERNICK 2,812,744

ERASER SUPPORT FOR mzcmmcm. PENCILS Filed April 14, 1954 INVENTOR JOHN MASTERNICK .BY 6% jjM/ AGENT ERASER SUPPORT FOR MECHANICAL PENCILS John Mastemiclr, Girard, Ohio Application April 14, 1954, Serial No. 423,073

2 Claims. (Cl. 120-38) The present invention relates to soca1led mechanical pencils, and more particularly to improvements in such pencils with respect to the adjustable support therein of removable eraser cartridges.

As its primary object the present invention seeks to provide an improved arrangement for the adjustable support of removable eraser cartridges in mechanical pencils whereby as the eraser wears through use the same may be adjusted and effectually retained in a new position, exposed for ready use.

Another object of the present invention is the provision of improved arrangements for the adjustable support of eraser cartridges in mechanical pencils, as above stated, wherein the improvement comprises a novel modification of certain conventional mechanical pencil designs, the invention contemplating amodification capable of economical accomplishment, requiring no material alterations in the manufacturing and assembly procedures now employed in the production of such conventional pencils.

in certain conventional mechanical pencils there is pro vided at the upper end of the pencil a cylindrical sleeve adapted for the reception and frictional retention of a cylindrical eraser cartridge, the upper end portion of the cartridge extending outwardly of the .sleeve in exposed relation, for ready use as the occasion arises. To support the inner end of the eraser cartridge there is provided a pedestal-like support having threaded interconnection with the body or principal component of the pencil, and as the eraser cartridge becomes worn through repeated use the support is rotated in its threaded socket so that the supporting surface is moved upwardly. This causes the eraser cartridge to be supported at a higher level than before, so that new portions of the eraser are exposed for use. However, I have found that as a general rule, apparently due to production expediences, the threaded interconnection between the pedestal-like support member and the body of the pencil is relatively loose, so that during normal usage of the pencil and of the eraser cartridge the support is caused to recede into its socket, even though the threaded interconnection is of a self-loclting type. This is apparently caused by normal vibrations, for example, and/or by continued pressure combined with considerable vibration during normal use of the eraser cartridge. Thus, when the support member recedes the eraser cartridge is similarly caused to recede into its retaining sleeve when pressure is applied, as during use of the eraser. In such cases continual readjustment of the eraser support is requiredan undesirable condition which is avoided by the teachings of my invention.

More specifically, the invention teaches the combining with the mechanical pencil mechanism described above of an extensible coil spring which acts between the pedestal-like eraser support and the body member of the pencil in such manner as to resiliently urge re eraser support in an extending direction. Thus, normal vibrations and the like which would otherwise cause the eraser nited rates atent 2,812,744 Patented Nov. 12, 1957 ice support to .recede as heretofore described, will, in my improved device, tend, if anything, to cause the support to further extend. Of course, the eraser cartridge is frictionally retained against such extending movement, and in accordance with the teachings of the invention the force of the spring is not such as will cause this force to be overcome.

Yet another specific object of the invention is the provision of an improved eraser supporting arrangement for the purpose and having the characteristics mentioned above which may be incorporated in certain existing mechanical pencil designs without modification of the standard components thereof. Rather, the invention contemplates the use in the standard conventional pencil of an additional member which may be readily incorporated into the pencil during assembly thereof, and without substantial modification of existing assembly procedures.

The above and other objects and advantages of my invention will become apparent upon full consideration of the following detailed specification and accompanying drawing wherein is shown a certain preferred embodiment of the invention.

In the drawing:

Figure 1 is an exploded view of a conventional mechanical pencil, representing the prior art in respect to whichmy invention represents an improvement;

Figure 2 is an assembled view, partly in section, of the mechanical pencil of Figure 1;

Figure 3 is an enlarged fragmentary View, partly in section, of a mechanical pencil of the general type shown in Figures 1 and 2, incorporating the teachings of my invention; and

Figure 4 is a second view of the apparatus of Figure 3.

'Referring now to the drawing, and initially to Figures 1' and 2 thereof, the reference numeral 10 designates the body member or principal component of-a convensleeve 14 may be gripped and rotated with respect to the body 10 to effect advancing and retracting of the writing lead 11. Generally, the sleeve 14 mounts a suitable clip 15' so that the pencil may be more readily carried from place to place.

As shown in Figure 2 the sleeve 14 is open at its upper or left hand end, and received in the sleeve at its upper end is a cylindrical eraser cartridge 15 which is so proportioned with respect to the inner walls of the sleeve 14 as to be frictionally gripped within the same. In the illustrated apparatus the cartridge 15 is provided at its inner end with a metal cap 16.

In normal usage of the eraser cartridge 15 considerable pressure is brought to bear upon the same through the pencil assembly so that the cartridge tends to move inwardly of the sleeve 14, the erasing pressure generally being considerably in excess of the frictional grip between the cartridge 15 and sleeve 14. Thus, to prevent such inward movement of the eraser 15 there is provided at the upper end of the body 10 a cap member 17 having a threaded bore 18 extending longitudinally therethrough, and a pedestal-like support 19, comprising a threaded shank portion 20 which engages the bore 18 and an enlarged head portion 21 which abuts against the capped inner end 16 of the eraser cartridge 15.

As the eraser is worn through use the exposed end thereof recedes toward the sleeve 14, and to compensate for such wear the support 19 is rotated with respect to the cap 17 so that the head portion 21 supports the cartridge at an extended position.

However, I have found that during normal use of the pencil the support 19 tends to recede inwardly of the cap 17, so that when the eraser is subsequently used no support is provided therefor and the cartridge is forced back into the sleeve 14. To avoid this I have provided, in accordance with the teachings of my invention, an extensible coil spring 22 which is assembled around the threaded shank portion 24 of the support in such manner as to act between the upper end of the cap 17 and the inner or lower face of the enlarged head portion 21 of the support 19.

In accordance with the preferred teachings of the invention the coil spring 22 is formed of very light spring wire, and is so constituted that in all positions of the support 19 a slight force is exerted upon the enlarged head portion 21, tending to move the support 19 outwardly of the cap 17. Thus, in the improved apparatus of Figures 3 and 4, normal vibrations and the like of the pencil assembly will tend to cause the support 19 to move outwardly of the cap 17, rather than inwardly as has been experienced with pencils of the type shown in Figures 1 and 2. Of course it will be understood that the cartridge 15 grips the inner walls of the cylinder 14 with considerably greater force than the eifective force exerted by the spring 22 tending to extend the support 19, so that the latter will remain exactly in its adjusted position at all times.

In Figure 4 the support 19 is illustrated in its inner most position, which, of course, is its adjusted position when the cartridge is new or substantially so. As will be readily understood the spring 22 should have a relatively small solid height so that the support 19 may be positioned as close as possible to the outer end of the cap 17. Or, alternatively, the cap 17 may be recessed or shortened to compensate for the displacement of the spring. This modification may be readily eifected without substantial modification or revision of present manufacturing procedures.

It should thus be apparent that I have carried out the various objects. of the invention, as stated. My invention represents a substantial improvement in arrangements for adjustably supporting eraser cartridges in conventional mechanical pencils in that the adjustable member is eifectually retained in its adjusted position at all times, whereas heretofore continual readjustment has frequently been required. Moreover, it will be evident that my invention may be carried out without material increase in manufacturing costs, and without any material modifications of existing manufacturing and assembly schedules and procedures. Thus, it is contemplated that the improvements of my invention may be readily embodied in certain of the conventional mechanical pencils currently commercially produced on a mass production basis without increase in the ultimate selling price of the product.

It should be understood, of course, that the embodiment herein specifically illustrated and described is intended to be representative only, as many modifications may be elfected within the clear teachings of the invention. Reference should therefore be made to the following appended claims in determining the full scope of the invention.

I claim:

1. In an eraser mounting of the type having a cylindrical sleeve, an eraser cartridge received in said sleeve and frictionally retained by the inner walls thereof, a pedestal-like member having an enlarged head portion adapted to bear against the inner end of said eraser cartridge to support the cartridge against inward movement in said sleeve, said pedestal-like member including a shank portion having a thread of shallow pitch, and means adjacent the inner end of said sleeve threadedly engaging said shank portion; the improvement comprising an extensible coil spring formed of very light spring wire received over said shank portion and acting upon said head portion and said last mentioned means whereby to exert a slight outward force on said pedestal-like member.

2. In an eraser mounting of the type having a cylindrical sleeve, an eraser cartridge received in said sleeve and frictionally retained by the inner walls thereof, and a support for engaging and supporting the inner end portion of said eraser cartridge, said support having a threaded portion with a thread of shallow pitch engaging other portions of said mounting whereby upon rotation of said support the position thereof with respect to said sleeve is altered; the improvement comprising yieldable means formed of very light spring material acting on said support whereby to exert a slight outward force upon said support.

References Cited in the file of this patent UNITED STATES PATENTS 1,530,558 Hansen Mar. 24, 1925 1,923,300 Deli et al Aug. 22, 1933 2,286,878 Tefft et a1. June 16, 1942 2,496,554 Lynn Feb. 7, 1950 

